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When to Plant Edamame in Washington County, MO

Edamame are soybeans harvested at the immature green stage for a sweet, nutty snack. They are high in protein and easy to grow in warm climates.

Washington County, Missouri is in USDA Zone 6b. The average last spring frost is April 10 and the first fall frost is October 24, giving you a growing season of approximately 197 days.

At an elevation of 738 feet, Washington County receives approximately 36.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Edamame during the growing season.

Washington County, MO (Zone 6b) Moderate season
197 days
Last Spring Frost April 10
197 growing days
First Fall Frost October 24

Washington County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (75 days to spare)
Transplant: Apr 5 🍅 Harvest: Jun 21 – Aug 2
Recommended (50%) ✓ Fits season (78 days to spare)
Transplant: Apr 10 🍅 Harvest: Jun 26 – Aug 7
Safe Start (90%) ✓ Fits season (76 days to spare)
Transplant: Apr 24 🍅 Harvest: Jul 10 – Aug 21

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 462 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Edamame needs ~1,269 GDD — county provides 2,856 GDD Excellent fit

Edamame Planting Timeline โ€” Washington County, MO

Edamame Planting Calendar

Activity When Date Range
Direct Sow April 17 Apr 17 โ€“ May 8
Harvest July 3 Jul 3 โ€“ Aug 14

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Direct Sow
May Direct Sow
June โ€”
July Harvest
August Harvest
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

75โ€“100 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 6b

Growing Season

197 days

Growing Tips for Washington County

Direct sow after soil is warm. Do not over-fertilize with nitrogen. Harvest when pods are plump and bright green but before they start to yellow. Steam or boil pods before eating.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Level Up Your Garden

Frequently Asked Questions

When should I plant Edamame in Washington County, MO?

Washington County is in Zone 6b with an average last frost of April 10. Plan your Edamame planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Washington County, MO?

Washington County, Missouri is in USDA Hardiness Zone 6b. The average last spring frost is April 10 and first fall frost is October 24.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Washington County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Washington County, MO. Local conditions may vary. Last updated: April 2026.